Method and apparatus for copying motion picture films



J. G. CAPSTAFF Aug. 13, 1935.

LMS

METHOD AND APPARATUS FOR COPYING MOTION PICTURE FI Filed June 24, 1933Patented Aug. 13, 1935 UNITED STATES PATENT OFFICE METHOD AND APPARATUSFOR COPYING MOTION PICTURE FILMS John G. Capstafl, Rochester, N. Y.,assignor to Eastman Kodak Company, Rochester, N. Y., a corporation ofNew York Application June 24, 1933, Serial No. 677,427

. Claims. (Cl. 88-24) This invention relates to a method of copyof thecamera be V; the necessary relation exing projectible pictures andparticularly to the pressed mathematically is l e-photographing of aprojected picture as part U 2 I of a scene of another motion picture. 5There are numerous instances in which it is desirable to include in amotion picture, scenes When the above relationship is maintained whichare not readily available at the place where each exposure m y the merawil inclu e the action or posed partof the picture is most a light and dperiod Of e proleeted Picture conveniently provided. This may be aooomand therefore it is immaterial at what point in plished by reproducingat the studio the desired the cycle o the projector t camera xp su 0setting or by photographing the actual sur eemmehees- In Operating the yt m i t nroundings and projecting the resulting pi t vention the speedsof the camera and projector in proper relation to the action or otherpart to Ordinarily w be maintained pp t y be added to form compositepicture equal but not necessarily equal, the amount of 5 It is an objectof thi i ve ti t provide permissible variation being discussed below. 5method of photographing either alone or com- Referring t s- 1 f th dawin th pr jector bined with other material a projected picture showndiagrammatically c udes a l g t ou ce without the proj t r d camerabeing i h l0 and condenser lenses II for concentrating the nized ormechanically or electrically coupled. light on a gate through which afilm is eo Another object of this invention is to provide a termittentlydrawn by a pull down mechanism ll method whereby projected pictures mayhe photoas is well known. A shutter I5 connected in any graphed so as tgive approximately equal ordinary way (not here shown) to rotate intimed posure to all frames and thereby remove the obrelation with thepull down d P v d d w t jectionable flicker generally arising from thetwo equally Spaced blades Periodically intercepts g5 stroboscopic natureof t exposure the light beam to an objective l6 which images 5 Otherobjects nd ad ant of t i lhventhe film l3 in the gate l2 onto atranslucent tion will be readily apparent from the following Screen oneOf the blades of the shutter descri tion when read in connection withthe interrupts the light during t pu l d wn op raaccompanying drawingand t scope will he tion and the other blade serves to increase thepointed out in the appended l i frequency of the light and dark screenperiods 30 In the drawing Fi 1 is 9, perspective view, so as to reduceflicker and is hereinafter-referred diagrammatically shown, of a systemfor copying as the flicker bladeby projecting a picture upon atranslucent screen The Camera for Photographing the image pmandphotographing the r j t d picture by jected on the screen II may be ofany standard transmitted light; Fig. 2 is a schematic view design d ishere shown in t a comprising a as showing the picture projected upon anopaqu gate member l8 past which a sensitive film I9 is screen andphotographing the projected picture adapted to he intermittently v d y aui by reflected light. able pull down mechanism 20. An objective 2| Inthe systems shown i Figs, 1 d 2 th images the screen I! on the film ISin the gate Hi to tures to be copied are projected on a screen and i andduring movement 0f the film the light is lo the projected picture isthen photographed either pted by a single b d shutter the angle bytransmitted or reflected light as desired. If of which may be adjustableduring use in y w th h t of t projector has N blades placed known mannerand which is connected to rotate equal angles apart and t opening of thecamera in timed relation with the pull down 20. Inasshutter is A, then,in order that all frames remuch Pmjector and Camera are 00111- 45 ceiveequal exposure irrespective of wh re1a mercial machines their completestructures have t positions the shutters f the projector and beenomitted from the drawing in the interest of camera occupied at thebeginning of the ex- Clea-mess and slmphcltyposure it is necessary thatthe camera shutter general opgmtion of the system in rotate an angle Ain the same time the projector Fig. 1 should be clear from the abovedescription 5o shutter rotates through an angle since the new featuresintroduced by the present invention relate primarily to theinter-relation of 2 5.. the designs and speeds of the two shutters. Withthe projector and camera running at approxi- 5 Now if the speed of theprojector be U and that mately equal speeds each frame 0! the picture 56without the usual mechanical film l3 will be imaged twice on the screenll with an intervening period of darkness which for convenience will beassumed to be equal and each frame on the sensitive film l9 will beexposed during one-half revolution of the shutter 15 in the projector.Now it is obvious that any 180 degree sector of the shutter IE5 willcontain the same amount of open sector as any other 180 degree sectorand accordingly the exposure of each frame in the camera for a periodequaling one half a revolution of the projector shutter 55 will resultin all of the exposures of the sensitive film I9 being substantiallyequal. p

In the arrangement shown in Fig. 2, the projector P images the film onan opaque screen 25 and this projected image is then photographed by thecamera C. the working of the system being identical with that shown inFig. 1 except that the screen 25 reflects the light to the camera ratherthan transmits it as does the screen I! shown in Fig. 1.

Since in practice the camera speed is usually fixed at feet a minutesmall changes in projector speedmay be compensated by small changes inthe camera shutter angle. A tachometer on the projector may have aremote indicator 26 in view of the cameraman who, if the projector speedchanges slightly, may adjust manually the shutter opening in the camera.

If, as in the Mitchell camera, the shutter angle '5 1'70 degrees and thecamera speed is 90 feet a minute the projector with a two bladedshutter, blades equally spaced, must run at a speed given by 2 V 2 90=fi=%=95.3 feet per minute.

A speed variation between the camera and projector up to plus or minus5% may be tolerated. A centrifugal speed control for the projector motorcan easily hold the speed well within this.

limit and therefore the problem of operating the camera and projector atsubstantially the same speed presents no practical difiiculty.

It will be seen that the present invention makes possible thephotographing of a projected picture or electrical coupling between thecamera and projector and therefore the system of this more flexible andeasier to handle than the ones in which such a coupling is necessary.

If it is desired to change in the copy film either the rate of actionwithout changing the projection speed or the projection speed withoutchanging the speed of action, it is only necessary to varycorrespondingly the speed of the projector and the shutter angle of thecamera in accordance with the principles above set forth.

By way of example, the following table has been prepared for a cameraman who wishes to compensate a. change in projection speed by a changein the camera shutter angle. It is assumed that the projector shutterhas two blades symmetrically placed and that the camera speed is 90 feetper minute.

Projector Camera shutter speed angle shutters of the limits. Theselimits would be such that no flicker would be notable in the finalprojected motion picture.

While this invention has been described in con-' nection with aprojector having a twmbladed shutter, it is to be understood that anydesired number of blades may be used as long as the requiredrelationship is made to exist between the projector and camera asoutlined above.

It is to be understood that the showing herein is largely diagrammaticand is not drawn to scale. The complete mechanical details necessary tocarry out my invention would, if shown in full, tend to obscure ratherthan reveal the invention. In practice thescreen l 1 would be ofconsiderable size and the proportions of the elements as shown are notat all accurate, the showing being merely that necessary to explain theprocess to one skilled in this art. In practice the arrangement shown inFig. 1, using a translucent screen, I consider far superior to thatshown in Fig. 2.

More than one projector may be used if it is desired to form a compositepicture and additional material may be included in the field of view ofthe camera as is well known.

The invention has been described in connection with two embodiments bymeans of which it may be practiced. Modifications will suggestthemselves to those skilled in the art without departing from the spiritof the invention, the scope of which is pointed out in the appendedclaims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In the art of copying motion picture film by photographing projectedimages of the picture on the film, the method of producing a film havinga number of frames corresponding to a certain amount of action whichdiifers from the number of frames on the original film corresponding tothe same amount of action, which method comprises intermittently movingat a uniform rate the original film, frame by frame, through a beam oflight which is directed to a screen, interrupting the light beam duringmovement of the film and at least once during the time each frame is 3.The method of reproducing from a motion picture film strip having aseries of image areas thereon upon another film strip in which thenumber of image action is different from that in the first strip whichcomprises moving both strips past printin windows at rates of speedwhich are diflerent with respect to the height of the respectiveprinting windows, projecting the image at one window upon the otherwindow, the movement of each film being intermittent, and interceptingthe projection beam at each window during the movement at the respectivewindow, the duration of a single exposure of one window being of thesame magnitude as the sum of the exposure and interception at the otherwindow.

4. The method oi! copying a motion picture film carrying a series ofpictures which comprises projecting a plurality of times and insuccession each picture of the series whereby each projection isfollowed by a dark period, independently making a series of singleexposures on a sensitive fiim from the projections from the picturefilin, timing each exposure to equal substantially the duration of alight and dark period of the projection, and separating the exposures bysubstantially equal intervals of time, whereby each exposure period ofthe sensitive film will include equal light and dark portions of theprojection regardless of the phase relation between the projections ofthe picture film and the exposures of the sensitive films.

5. The method of copying a motion picture film carrying a series ofpictures onto a sensitive film the movement of the two filmswhichcomprises projecting a plurality of times and in succession eachpicture of the series, whereby each projection 15 followed by a darkperiod, photographing the projected pictures by making a series ofexposures on a sensitive film for an interval or time substantiallyequal to the period covered by a light and dark period in the projectedpicture, and separating the exposures of 20 said series by an equalperiod of time.

JOHN G. CAPSTAFF.

